NC0000272_Preliminary Evaluation Revised Operations_20230317

Preliminary Evaluation and Recommendations for Revised
WWTP Operations, Pactiv Evergreen — Canton, N. C. Mill
Background and current Status
At the request of Pactiv Evergreen, Environmental Business Specialists, LLC (EBS) were asked to
evaluate the Canton North Carolina mill wastewater treatment system from the perspective of
operating this system in the event of a permanent shutdown of the mill.
The Canton mill is a fully integrated bleached pulp mill. The mill's wastewater treatment
system is an activated sludge biological system that includes primary clarification, aeration,
aerobic digestion, secondary clarification, and oxygen addition. The treated effluent from the
Canton Mill discharges into the Pigeon River. The sludges produced from the primary and
secondary treatment are dewatered on site by belt press dewatering equipment and then
landfilled in a mill owned landfill. The mill's wastewater system also handles the wastewater
from the Town of Canton, North Carolina. The flow from the Town is estimated to be
approximately 1 MGD and experiences increases in flow during rain events.
Summary of Recommendations
After evaluating the Canton Mill's wastewater treatment system EBS developed the following
recommendations and plan to transition the mill's wastewater system from handling mainly a
fully bleached pulp mill and municipal wastewater to only municipal wastewater with a small
amount of industrial wastewater (landfill leachate and stormwater runoff from the mill site).
Based upon EBS experience with these types of wastewater systems the transition of the
system would be divided into three distinct phases.
Phase I — Initial Shutdown of the mill operations
Phase I would also be further divided into a preparatory phase prior to the actual ceasing of
operations, followed by the actual shutdown of the mill equipment.
The preparatory phase or Phase IA would involve all necessary preparations to maintain control
of the wastewater loading generated during the initial shutdown for the purpose of maintaining
the efficient treatment of the wastewater system and maintaining compliance with the mill's
existing NPDES wastewater discharge permit. Phase IA would be very similar to preparations
made by any pulp mill when going into a major mill outage. Important aspects of Phase IA
would be as follows:
• Controlling and maintaining a circumneutral pH.
• Having surge volume, if possible, to impound high strength wastewater to allow
controlled flow to the activated sludge system.
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• Maintaining adequate inventories of sulfuric acid and carbon dioxide for pH control.
Coagulants and polymers for WWTP upset solids control, and supplemental nutrients.
• Development of coordinated vessels draining plans to allow the wastewater system to
better assimilate the mill wastewater and not be overwhelmed by volume or loading
created from the shutdown.
Phase 1B would be the actual ceasing of operations and initial draining of tanks, vessels, piping,
and other mill equipment. The BOD loading expected during this time would be similar to
major mill maintenance outages and could last from several days to 2-3 weeks. During this
phase it is recommended to continue to operate the wastewater system at full capacity to
process and treat the wastewater generated from the mill. The mill should continue to monitor
flow, BOD/surrogate loading, Food/Microorganism (F/M) ratio, and pH. The end of this phase
would be signaled by a significant and sustained decrease in hydraulic and organic (BOD)
loading. EBS recommends that when the mill flow and loading is 50% of normal for a sustained
period such as a 3-5 day rolling average, then the mill can begin to transition to Phase II.
Phase II —Tank, vessel, mill, and piping clean-up
Phase II would be similar to the end of major maintenance outages where significant reductions
in flow and loading are experienced. This phase could last several months and as a result the
wastewater system would experience much lower flow and BOD loading. During this phase the
wastewater system would start experiencing permanent changes in loading and could need to
start being downsized to maintain treatment efficiency. Excess equipment could be taken out
of service in response to the lower loading and flow. Equipment that can be evaluated for
removal from service during this phase are primary clarifiers, discontinuing the use of CO2 for
pH control, secondary clarifiers, various pumps required to pump wastewater such as the low
lift pumps, and one of the two aeration trains. Additionally, the number of operating Belt
Presses may also be reduced. While EBS's initial recommendation is to continue operating the
aeration trains in the activated sludge mode, there is the likelihood that loading and flow will
not be sufficient to support activated sludge operation. If so, EBS's recommendation would be
to move to Phase III and change the operation of the aeration system to a once through ASB
(Aerated Stabilization Basin).
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Phase III — Mill flow and loading approaches zero.
In this phase the primary source of wastewater to the treatment system will be the Town of
Canton. Expected flow will be 1 MG except during rain events. When this phase is reached it
is EBS's recommendation that the wastewater system be downsized to the following:
• Primary Treatment—Grit Chamber, Bar Screen, Low Lift pump system, and flow splitting
station would continue.
• Primary Clarification—The #1 Primary clarifier would receive normal flow from the
Town with Nos. 2&3 out of service but available to impound storm surge flows.
• Secondary Treatment—One aeration train would be operated in a once through ASB
mode of operation with the first 2.3 MG section being fully aerated and the second 3.4
MG section being aerated with a final settling zone at the discharge end.
• Secondary/Tertiary Clarification -The #6 or #5 clarifier would receive normal flow from
the aeration train with the other two secondary clarifiers being out of service but
available for emergency use such as additional storm surge or upset impoundment of
flow from secondary treatment.
• Final discharge—the flume, reaeration cascade (02 injection) and flow measurement
would be continued as required to maintain compliance with the NPDES discharge
permit.
Further Investigation & Data Needs
EBS requested additional information to fully confirm its recommendations and conclusions and
fully characterize the wastewater coming from the Town of Canton:
• Any Industrial components in the Town's wastewater. A brewery, plastic
extrusion facility, and commercial dry cleaner may all discharge to the Town's
collection system. With the mill no longer providing dilution flow there maybe
constituents of concern from these dischargers.
• Nitrogen and ammonia content of the Canton wastewater.
• Further investigation of the normal and maximum/minimum flows that would be
expected from the Town of Canton.
• Characterization of the landfill leachate and review of the mill's last NPDES
permit priority pollutant analysis.
• Mill WWTP operator input and review of these recommendations and transition
plan.
• A treatability study at the Mandeville lab to confirm the residence time needed
to treat the Town of Canton wastewater stream using the once through ASB
mode of operation.
The week of March 20, sampling and analysis will be completed to further characterize
wastewater and to add more detail the transition plan.
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